From cc907c0f162ee84e5698b9c27ac6fb0be8bb9bc0 Mon Sep 17 00:00:00 2001
From: Martin Szulecki
Date: Wed, 22 Oct 2014 02:14:52 +0200
Subject: Workaround autoconf bug and ensure a C++ compiler is mandatory

If AC_PROG_CXX is used after AC_PROG_CC, it will return "g++" even if no
C++ compiler is installed. However, as we need one, testing compiling a
program will make configure fail if indeed no C++ compiler is installed.
---
 configure.ac | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/configure.ac b/configure.ac
index fb6b196..b9185a6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -27,6 +27,16 @@ AC_SUBST(LIBXML2_VERSION)
 # Checks for programs.
 AC_PROG_CC
 AC_PROG_CXX
+
+# AC_PROG_CXX will return "g++" even if no c++ compiler is installed
+AC_LANG_PUSH([C++])
+AC_MSG_CHECKING([whether $CXX is available and compiles a program])
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],[])],
+                  [AC_MSG_RESULT([yes])],
+                  [AC_MSG_RESULT([no])
+                   AC_MSG_ERROR([C++ compiler not available or unable to compile])])
+AC_LANG_POP
+
 AM_PROG_CC_C_O
 AC_PROG_LIBTOOL
 
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